Letters Patent of Canada No. 1014,240 granted to Noma Lites Canada Limited, discloses a lamp string assembly including a dual-wire power cord being, preferably, the well known ripcord with twin parallel wires; each including an electrical conductor in a penetrable insulating casing detachably bonded to the casing of the other wire, and at least one lamp socket molded onto an intermediate portion of the power cord.
The lamp socket has a shell or body molded of electrical insulating material including, a receptacle for the base of an electric lamp; a junction compartment co-axial and integral with the receptacle and within which the power cord is receivable and connected to the socket, and an integral partition separating the receptacle and the junction compartment. The terminals or current conductors of each socket extend from the junction compartment, through the partition, and into the receptacle to engage the base of a lamp installed therein and to make electrical connection therewith. A spike provided on each said terminal extends into the junction compartment where it impales one of the power cord wires so as to penetrate the insulating casing thereof and effect electrical engagement with the conductor containd therein.
Within the junction compartment the partition provides a dike which intervenes between the wires separating them from each other in the zone of their impalement upon the spikes; the said spikes together with the wires impaled thereon being also encapsulated by the partition.
The physical separation of the wires of the power cord has proven useful in discouraging arcing between them at the points of their impalement--particularly, in the presence of moisture and the prevention of arcing has been enhanced by erecting the dike aforesaid between them as well as by encapsulating the wires and spikes in the dielectric socket material in the junction compartment.
The patent aforesaid also shows it to be common to provide small holes in the socket for drainage of liquids--e.g. rain water--collecting in its receptacle portion.
The construction of the described socket is such as to adapt it to mass production techniques enabling efficient and economical manufacture of lamp string assemblies which are usually durable and relatively trouble free. However, certain problems have become manifest in connection therewith which the present invention seeks to obviate.